1. Field of the Invention
This invention relates to electronic engine controls for an internal combustion engine.
2. Prior Art
It is known to use heated oxygen sensors in the exhaust gas from an internal combustion engine to produce a signal indicative of the amount of oxygen in the exhaust gas. An exhaust gas oxygen sensor operates with an improved efficiency within a certain temperature range. It is desirable to get the temperature of the exhaust gas oxygen sensor to be within this temperature range quickly.
Referring to FIG. 1, during startup of an engine, in accordance with a known circuit, approximately 14 volts of electricity from a battery 10 flows to a node 11 where the current is split between two paths. One path leads half of the total current through a HO2S 12 to a switch 13 which is typically closed during engine startup and also running mode as needed. From switch 13 the flow concludes at a battery ground 17. The other path leads the other half of the total current through a HO2S 14 to a switch 15 which also remains closed during engine startup and operating mode. The flow ends at battery ground 17. A bridge resistor 16 is used to periodically check the current through each path by opening one of the switches. In operation, the current through the HO2S's is the same during start-up as during normal operation. It would be desirable to get a faster initial warm up. These are some of the problems this invention overcomes.